Unfortunately the biking Layer also doesn't fix any of this. It only appears to highlight "cycling-friendly" streets here, but the results look random at best here.

Sounds like a data problem over a software problem.

The fact that what the cycling layer shows to me is useless is a data problem, yes. However, As I mentioned in my comment above, as a cyclist I care about seeing a visualization of my surroundings. OSM tells me at a glance if an area I want to cycle through is a forest, if there is public transit, etc. None of that is part of Google's cycling layer, or any other layer - apart from transit. But the faint lines added by the transit layer are not helping, either. The maps are an unreadable low-contrast mess.